The Microscope – Volume 71, Fourth Quarter 2024
IN THIS ISSUE (NOW SHIPPING)
On the cover
Gymnosperm cross-field pits, adjacent to tracheids that also contain bordered pits, are evident in this char particle from wildfire smoke. See Assemblage Analysis and the Microscopical Identification of Particle Sources: Wildfire, a Case Study, page 147. (Photomicrograph courtesy of Russ Crutcher/Microlab Northwest)
Editorial | A Guide for Authors, Readers, and Researchers
Gary J. LaughlinThe Microscope 71:4, p. ii, 2024https://doi.org/10.59082/PZVM6754
Excerpt: You asked for it (and even if you didn't), you got it. Included here are some of the general policies as they pertain to The Microscope Journal and Microscope Publications (a Division of McCrone Research Institute). Thank you for reading, writing, and subscribing.
Assemblage Analysis and the Microscopical Identification of Particle Sources: Wildfire, a Case Study
Russ Crutcher and Heidie CrutcherThe Microscope 71:4, pp. 147–160, 2024https://doi.org/10.59082/YIIC3662
Abstract: Assemblage analysis is the use of multiple particle types created by a source to identify and quantify the presence of particles from that source. The approach presented here is limited to the case of debris from wildfires though it is applicable to tracking any particle source. The first step in applying this method is to characterize the source and to identify and characterize the particles created. The particles carry their identity in their optical properties but much more than their identity is present. Artifacts including size, texture, color, surface features, internal structure, and more than forty additional optical properties provide a history of the particle and its source. It requires a microscope capable of examining a single field of view with transmitted brightfield, darkfield, linear polarized light, crossed polarized light, circularly polarized light, and reflected darkfield illumination in sequence and together without moving the slide and doing so in seconds.
Critical Focus | Focusing on Microscopy − Books that Open Our Eyes
Brian J. Ford
The Microscope 71:4, pp. 161–173, 2024https://doi.org/10.59082/DZZM8759
Excerpt: When first I wrote books on the microscope, I had only one or two historic titles on my own bookshelves. Now I have hundreds. Curiously, it was writing my own books that led me to acquire the others, and they inspire me every day. Their authors have bequeathed to us a wealth of insight, and we can watch our science unfolding as we move from one book to the next.
A Re-Evaluation of Refractive Index and Dispersion Measurements Using the Hot-Stage Immersion Method for Additional Discrimination of Automotive Glass
Gwenith Zydlewski and Patrick Buzzini
The Microscope 71:4, pp. 175–186, 2024
https://doi.org/10.59082/LNRA8132
Abstract: The refractive index (RI) is a fundamental property of glass, and the hot-stage immersion method is an established method for its examination in a forensic setting. Motivated by a discordant body of literature regarding the contribution of dispersion and the use of alternative monochromatic filters compared with the commonly used sodium D-line at 589 nm, this study aimed to evaluate the discriminating capabilities of the three monochromatic Fraunhofer F, D, and C-lines at 486 nm, 589 nm, and 656 nm, respectively, as well as the dispersive index, using four sample sets from a total of 36 automotive glass samples known to have close-range RI values. The study revealed that, in general, assessing and calculating the dispersive index (ν) from the refractive index values of the three Fraunhofer lines did not provide any further differentiation among the automotive glass samples examined in this research. Additionally, analysis of the individual filters revealed that the traditional D-line provided the lowest discrimination capabilities. In contrast, using the blue filter (F-line) and, in some instances, the red filter (C-line) considerably improved these capabilities, prompting a re-evaluation of the practice of measuring glass refractive index in forensic laboratories.
The Microscope Author and Subject Indexes: Volume 71, 2024
The Microscope 71:4, pp. 188–191, 2024
Afterimage | Hopper Crystal
Kelly M. Brinsko Beckert — Microtrace LLCThe Microscope 71:4, p. 192, 2024
Manganese carbonate crystal with an interesting hopper crystal morphology. Secondary electron imaging with the scanning electron microscope (SEM) and 20 keV accelerating voltage, original magnification = 5000×. Runner-up photomicrograph at the Inter/Micro 2024 Photomicrography Competition in Chicago.
Manganese carbonate crystal with an interesting hopper crystal morphology. Secondary electron imaging with the scanning electron microscope (SEM) and 20 keV accelerating voltage, original magnification = 5000×. Runner-up photomicrograph at the Inter/Micro 2024 Photomicrography Competition in Chicago.
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